Oil filters to remove impurities from engine oil are found in virtually all internal combustion engines of the four cycle type. Such oil filters are removed and are replaced or cleaned often during the life of the engine thereby cleaning the oil circulating within the engine and extending engine life.
Typically, the oil filter is removed and replaced during scheduled maintenance sessions at a garage or other automotive or truck service center by mechanics or others who service such engines. In the course of a workday, many such filters are removed and replaced.
When the filter is removed, it is usually filled with oil because the filter is positioned on the bottom of the engine. The axis of the filter is rarely vertical because the filter may be located by the engine designers to be in a most convenient place for removal and position of the filter in that location is not of primary concern. Even if the filter is vertical, however, oil is usually spilled from the filter during removal. This spillage runs over the user who is handling the filter and onto the floor or undercarriage of the vehicle on which the filter is installed. It is inconvenient, environmentally contaminating and inefficient since the spillage must be cleaned. It is also a nuisance.
There is disclosed in Verdegan et al U.S. Pat. No. 5,462,679 an air inlet on the casing of an oil filter. Verdegan et al teach using compressed air to clean the oil filter so it may be reused. The air must be injected into the central area or cavity of the oil filter because a back or reverse flow is needed to clean the filter and, thereafter, the oil is drained from a drainplug.